Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 764,219	$ 739,385	$ 429,072
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, amortization and accretion	965,437	694,698	391,844
Property impairments	220,508	122,274	108,458
Non-cash (gain) loss on derivatives, net	130,196	(199,737)	(4,057)
Stock-based compensation	39,890	29,057	16,572
Provision for deferred income taxes	442,621	405,294	245,203
Excess tax benefit from stock-based compensation	0	(15,618)	0
Dry hole costs	9,350	767	7,949
Gain on sale of assets, net	(88)	(136,047)	(20,838)
Other, net	2,037	5,007	3,661
Changes in assets and liabilities:
Accounts receivable	(166,138)	(91,791)	(294,702)
Inventories	(7,697)	(7,165)	(3,412)
Prepaid expenses and other	(11,537)	14,381	(3,329)
Accounts payable trade	107,250	(8,487)	83,907
Revenues and royalties payable	28,401	40,030	88,976
Accrued liabilities and other	44,260	40,309	20,784
Other noncurrent assets and liabilities	(5,414)	(292)	(2,173)
Net cash provided by operating activities	2,563,295	1,632,065	1,067,915
Cash flows from investing activities:
Exploration and development	(3,660,773)	(3,493,652)	(1,925,577)
Purchase of producing crude oil and natural gas properties	(16,604)	(570,985)	(65,315)
Purchase of other property and equipment	(62,054)	(53,468)	(44,750)
Proceeds from sale of assets and other	28,420	214,735	30,928
Net cash used in investing activities	(3,711,011)	(3,903,370)	(2,004,714)
Cash flows from financing activities:
Revolving credit facility borrowings	970,000	2,119,000	493,000
Repayment of revolving credit facility	(1,290,000)	(1,882,000)	(165,000)
Proceeds from issuance of Senior Notes	1,479,375	1,999,000	0
Proceeds from issuance of common stock	0	0	659,736
Proceeds from other debt	0	22,000	0
Repayment of other debt	(1,951)	(1,579)	0
Debt issuance costs	(2,265)	(7,373)	(36)
Equity issuance costs	0	0	(368)
Repurchase of equity grants	(14,690)	(11,236)	(4,918)
Excess tax benefit from stock-based compensation	0	15,618	0
Exercise of stock options	0	60	13
Net cash provided by financing activities	1,140,469	2,253,490	982,427
Net change in cash and cash equivalents	(7,247)	(17,815)	45,628
Cash and cash equivalents at beginning of period	35,729	53,544	7,916
Cash and cash equivalents at end of period	$ 28,482	$ 35,729	$ 53,544